firefox/toolkit/components/extensions/parent/ext-geckoProfiler.js

/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
/* vim: set sts=2 sw=2 et tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this file,
 * You can obtain one at http://mozilla.org/MPL/2.0/. */

"use strict";

const PREF_ASYNC_STACK = "javascript.options.asyncstack";

const ASYNC_STACKS_ENABLED = Services.prefs.getBoolPref(
  PREF_ASYNC_STACK,
  false
);

var { ExtensionError } = ExtensionUtils;

ChromeUtils.defineLazyGetter(this, "symbolicationService", () => {
  let { createLocalSymbolicationService } = ChromeUtils.importESModule(
    "resource://devtools/client/performance-new/shared/symbolication.sys.mjs"
  );
  return createLocalSymbolicationService(Services.profiler.sharedLibraries, []);
});

const isRunningObserver = {
  _observers: new Set(),

  observe(subject, topic) {
    switch (topic) {
      case "profiler-started":
      case "profiler-stopped":
        // Call observer(false) or observer(true), but do it through a promise
        // so that it's asynchronous.
        // We don't want it to be synchronous because of the observer call in
        // addObserver, which is asynchronous, and we want to get the ordering
        // right.
        const isRunningPromise = Promise.resolve(topic === "profiler-started");
        for (let observer of this._observers) {
          isRunningPromise.then(observer);
        }
        break;
    }
  },

  _startListening() {
    Services.obs.addObserver(this, "profiler-started");
    Services.obs.addObserver(this, "profiler-stopped");
  },

  _stopListening() {
    Services.obs.removeObserver(this, "profiler-started");
    Services.obs.removeObserver(this, "profiler-stopped");
  },

  addObserver(observer) {
    if (this._observers.size === 0) {
      this._startListening();
    }

    this._observers.add(observer);
    observer(Services.profiler.IsActive());
  },

  removeObserver(observer) {
    if (this._observers.delete(observer) && this._observers.size === 0) {
      this._stopListening();
    }
  },
};

this.geckoProfiler = class extends ExtensionAPI {
  getAPI(context) {
    return {
      geckoProfiler: {
        async start(options) {
          const { bufferSize, windowLength, interval, features, threads } =
            options;

          Services.prefs.setBoolPref(PREF_ASYNC_STACK, false);
          if (threads) {
            Services.profiler.StartProfiler(
              bufferSize,
              interval,
              features,
              threads,
              0,
              windowLength
            );
          } else {
            Services.profiler.StartProfiler(
              bufferSize,
              interval,
              features,
              [],
              0,
              windowLength
            );
          }
        },

        async stop() {
          if (ASYNC_STACKS_ENABLED !== null) {
            Services.prefs.setBoolPref(PREF_ASYNC_STACK, ASYNC_STACKS_ENABLED);
          }

          Services.profiler.StopProfiler();
        },

        async pause() {
          Services.profiler.Pause();
        },

        async resume() {
          Services.profiler.Resume();
        },

        async dumpProfileToFile(fileName) {
          if (!Services.profiler.IsActive()) {
            throw new ExtensionError(
              "The profiler is stopped. " +
                "You need to start the profiler before you can capture a profile."
            );
          }

          if (fileName.includes("\\") || fileName.includes("/")) {
            throw new ExtensionError("Path cannot contain a subdirectory.");
          }

          let dirPath = PathUtils.join(PathUtils.profileDir, "profiler");
          let filePath = PathUtils.join(dirPath, fileName);

          try {
            await IOUtils.makeDirectory(dirPath);
            await Services.profiler.dumpProfileToFileAsync(filePath);
          } catch (e) {
            Cu.reportError(e);
            throw new ExtensionError(`Dumping profile to ${filePath} failed.`);
          }
        },

        async getProfile() {
          if (!Services.profiler.IsActive()) {
            throw new ExtensionError(
              "The profiler is stopped. " +
                "You need to start the profiler before you can capture a profile."
            );
          }

          return Services.profiler.getProfileDataAsync();
        },

        async getProfileAsArrayBuffer() {
          if (!Services.profiler.IsActive()) {
            throw new ExtensionError(
              "The profiler is stopped. " +
                "You need to start the profiler before you can capture a profile."
            );
          }

          return Services.profiler.getProfileDataAsArrayBuffer();
        },

        async getProfileAsGzippedArrayBuffer() {
          if (!Services.profiler.IsActive()) {
            throw new ExtensionError(
              "The profiler is stopped. " +
                "You need to start the profiler before you can capture a profile."
            );
          }

          return Services.profiler.getProfileDataAsGzippedArrayBuffer();
        },

        async getSymbols(debugName, breakpadId) {
          return symbolicationService.getSymbolTable(debugName, breakpadId);
        },

        onRunning: new EventManager({
          context,
          name: "geckoProfiler.onRunning",
          register: fire => {
            isRunningObserver.addObserver(fire.async);
            return () => {
              isRunningObserver.removeObserver(fire.async);
            };
          },
        }).api(),
      },
    };
  }
};